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What are food additives and impurities?
Last reviewed: 04.07.2025
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Additives are chemical substances mixed with food products to facilitate processing, storage or enhance their organoleptic properties. Only those additives that have passed certain laboratory tests are permitted for use as food.
The benefits of additives (e.g., reduced waste, increased food variety, prevention of food poisoning) versus risks are difficult to assess. For example, nitrite, which is used in cured meats, prevents the growth of Clostridium botulinum and improves flavor. However, nitrite is converted to nitrosamines, which are carcinogenic to animals. On the other hand, the amount of nitrite added to cured meats is small compared to the amount of nitrates found in natural foods, which are converted to nitrite by the salivary glands. Vitamin C in food can reduce the formation of nitrite in the gastrointestinal tract. Rarely, some additives (e.g., sulfites) cause hypersensitivity reactions (food allergies). Most reactions are caused by common foods.
Adulterants sometimes cannot be completely removed without destroying the food; therefore, limited amounts are permitted. The main adulterants are pesticides, heavy metals (lead, cadmium, mercury), nitrates (in green leafy vegetables), aflatoxins (in nuts and milk), growth-promoting hormones (in dairy products and meat), animal hair and feces, and insect parts. The U.S. Food and Drug Administration (FDA) has developed safe levels of adulterants that do not cause illness or adverse effects in humans. However, the relationship between extremely low levels of exposure and adverse effects has been shown to be difficult to assess; long-term side effects, although undesirable, are possible. Safe levels are often determined by consensus rather than by hard evidence.